 I will create a sample DECLARE model for a Purchase-to-Pay (P2P) process based on the given constraints and assuming the following activities: `Request Purchase Order` (RPO), `Create Purchase Order` (CPO), `Goods Received` (GR), `Invoice Received` (IR), `Check Invoice` (CI), `Approve Invoice` (AI), `Purchase Order Completed` (POC), `Make Payment` (MP), and `Close Account` (CA).

Note that the support and confidence are set to 1.0 for all rules as you requested, but in a real-world scenario, these values should be calculated based on historical process data.

```python
declare_model = {
    'existence': {'RPO': {'support': 1.0, 'confidence': 1.0}},
    'existence': {'CPO': {'support': 1.0, 'confidence': 1.0}},
    'existence': {'GR': {'support': 1.0, 'confidence': 1.0}},
    'existence': {'IR': {'support': 1.0, 'confidence': 1.0}},
    'existence': {'CI': {'support': 1.0, 'confidence': 1.0}},
    'existence': {'AI': {'support': 1.0, 'confidence': 1.0}},
    'existence': {'POC': {'support': 1.0, 'confidence': 1.0}},
    'existence': {'MP': {'support': 1.0, 'confidence': 1.0}},
    'existence': {'CA': {'support': 1.0, 'confidence': 1.0}},

    'init': {'RPO': {'support': 1.0, 'confidence': 1.0}},

    'responded_existence': {'CPO': {'RPO': {'support': 1.0, 'confidence': 1.0}}},
    'coexistence': {'CPO': {'GR': {'support': 1.0, 'confidence': 1.0}}},
    'response': {'IR': {'CPO': {'support': 1.0, 'confidence': 1.0}}},
    'precedence': {'CI': {'IR': {'support': 1.0, 'confidence': 1.0}}},
    'succession': {'AI': {'CI'}},
    'succession': {'POC': {'AI'}},
    'exactly_one': {'MP': {'support': 1.0, 'confidence': 1.0}},

    'altresponse': {'GR': {'RPO': {'support': 1.0, 'confidence': 1.0}}},
    'altprecedence': {'IR': {'CPO'}},
    'altsuccession': {'CI': {'AI'}},
    'chainresponse': {'MP': {'POC'}},
    'chainprecedence': {'CA': {'MP'}},
    'chainsuccession': {'CA': {'MP', 'POC'}},

    'noncoexistence': {'RPO': {'CA': {'support': 1.0, 'confidence': 1.0}}},
    'nonsuccession': {'CA': {'MP'}},
    'nonchainsuccession': {'CA': {'MP', 'POC'}}
}
```

This DECLARE model represents a P2P process where the sequence of activities goes as follows: Request Purchase Order -> Create Purchase Order -> Goods Received (coexists) -> Invoice Received (response) -> Check Invoice (precedence) -> Approve Invoice (succession with CI and POC) -> Purchase Order Completed (succession with AI) -> Make Payment (exactly one) or Close Account (non-coexistence, nonsuccession, nonchainsuccession).

It also enforces alternate sequences, chain relationships, and specific activity occurrences to ensure that the process complies with business rules.